In recent years, a zero intermediate frequency technology is widely applied to radio receivers. The zero intermediate frequency technology has the following advantages: Less intermediate frequency receiving links are used, and complexity of an intermediate frequency design, a size of a board, and hardware costs are reduced. A working principle of a zero intermediate frequency radio receiver is: A radio frequency analog signal is input to a quadrature demodulator, and the quadrature demodulator performs quadrature demodulation on the radio frequency analog signal and outputs a baseband composite signal to a digital signal processor. The quadrature demodulator cannot ensure an absolute quadrature, and image leakage occurs. Consequently, an image signal is generated. Such an image signal affects quality of a received signal in a radio receiver, and the received signal needs to be calibrated.